Smoke Alarms, Carbon Monoxide Alarms, and Legionella: What Every Landlord Must Do

CO alarms are now required in every room with any fixed combustion appliance — including gas boilers, since the 2022 rules. Legionella is a risk assessment duty, not a certificate. Here's the full picture.

Three safety obligations trip up landlords more than most: a carbon monoxide alarm requirement that was extended in 2022 but is still widely misapplied, a Legionella duty that is either ignored entirely or turned into an unnecessary expense, and a smoke alarm test obligation that must happen on the first day of every tenancy. None of these rules are new — but all three are still frequently misunderstood.

Smoke alarms

The Smoke and Carbon Monoxide Alarm (Amendment) Regulations 2022 require landlords in England to install at least one working smoke alarm on every storey that is used as living accommodation.

Any floor with a room used wholly or partly as living accommodation — bedrooms, sitting rooms, kitchens, dining rooms — requires a smoke alarm. A floor used only for storage does not. A loft conversion used as a bedroom requires one; a loft used only for storage does not.

The first-day test

The Regulations place a specific duty on landlords: smoke alarms and CO alarms must be tested on the first day of each new tenancy and must be in working order at that point. A written record of the test date and result is your evidence of compliance. During the tenancy, the responsibility for routine testing shifts to the tenant — but if an alarm is reported faulty, the landlord must repair or replace it promptly.

The civil penalty for breach is up to £5,000.

Carbon monoxide alarms

This is where many landlords are non-compliant without knowing it. The 2022 amendment extended the CO alarm requirement to every room used as living accommodation that contains a fixed combustion appliance — not just rooms with solid fuel appliances as before. From October 2022, this includes:

Gas boilers (if located in a room used as living accommodation)
Gas fires
Open fireplaces and log burners
Oil-fired appliances

Gas cookers are explicitly excluded. A kitchen with only a gas cooker does not need a CO alarm on that basis alone.

For most properties, the practical effect is straightforward: if the boiler is in the kitchen, the kitchen needs a CO alarm. If the boiler is in an airing cupboard that is accessed from but separate to a living space, check whether the cupboard itself qualifies as "living accommodation".

Alarm standards and replacement

CO alarms should conform to British Standard EN 50291. Replace alarms at the end of their stated working life — typically 5 to 7 years for CO alarms. The expiry or replacement date is usually marked on the unit.

Legionella

Legionella is the most misunderstood obligation in residential landlord compliance. Here is what the law actually requires.

The duty: risk assessment, not certificate

Under the Health and Safety at Work etc. Act 1974 (HSWA) and the Control of Substances Hazardous to Health Regulations (COSHH), landlords must assess and manage the risk of Legionella bacteria in water systems at their rental properties. The applicable approved code of practice is L8 (Legionnaires' disease: The control of legionella bacteria in water systems).

What the law does not require:

Microbiological water testing (testing for Legionella in water samples)
Annual or biennial reviews on a fixed schedule
A "Legionella certificate" — HSE is explicit that no such certificate is required by law

A written risk assessment recording what you checked and found is your evidence of compliance. Landlords are not required to formally record their findings, but HSE notes it is wise to do so.

Who can do the assessment

For most standard domestic rental properties, the risk is low and the landlord can carry out the assessment themselves without a specialist contractor. HSE guidance describes a straightforward process:

Check for dead ends in the pipework (sections that are rarely or never flushed)
Ensure hot water is stored above 60°C
Ensure cold water is kept below 20°C
Flush little-used outlets (showers, taps in spare rooms) regularly, particularly after a void period

The assessment needs more attention for properties with water storage tanks (header tanks, cold water cisterns), complex plumbing with dead-end sections, or where tenants are known to be immunocompromised.

When to review

The law does not prescribe a fixed review interval. Review the assessment when something changes: new pipework, a long void period, a change in tenants. For properties with mains-fed combi boilers and no stored water, a review at each change of tenancy is generally proportionate.

The enforcement position

HSE and local authority inspectors do not proactively inspect domestic rental premises to check for Legionella risk assessments. However, if a tenant contracts Legionnaires' disease from the property's water system, the landlord may face prosecution under the HSWA and must demonstrate they fulfilled their duty of care. A written record of the assessment and any control measures is what you would need to produce.

Keeping it all tracked with mypy

mypy's certificate tracking covers smoke alarm, CO alarm, and Legionella risk assessment records alongside gas and EICR obligations — with reminders before you need to act. The compliance hub shows the status across your entire portfolio at a glance. Free for up to 2 properties.

Frequently asked questions

I have a gas boiler in my kitchen. Do I need a CO alarm there?

Yes. A gas boiler is a fixed combustion appliance. Since the 2022 amendment, any room that is used as living accommodation and contains a fixed combustion appliance requires a CO alarm. The kitchen is living accommodation, so a CO alarm is required if the boiler is located there.

My tenant says the smoke alarm keeps beeping. Whose responsibility is that?

A low-battery warning (intermittent single beep) is the tenant's responsibility during the tenancy — they should replace the battery. If the alarm unit is faulty and needs replacing, that is the landlord's responsibility. Replace faulty alarms promptly.

Do I need a contractor for the Legionella risk assessment?

Not for most standard domestic lets. For a property with a combi boiler and mains-fed water (no storage tanks), a landlord can carry out the assessment themselves using HSE guidance at no cost. A contractor is sensible for properties with storage tanks, complex systems, or vulnerable tenants.

I have never done a Legionella risk assessment. Do I need to backdate one?

You cannot genuinely backdate an assessment. Carry it out now and document what you find. Going forward, update the record when anything changes. Acting now is better than remaining in breach.

Is there a prescribed form for recording the first-day alarm test?

No. A note on the tenancy file recording the property address, the date, which alarms were tested, and that they were found to be working is sufficient. Keep it with your tenancy documents.

Sources

This article is general guidance, not legal advice. Verify your obligations against current GOV.UK guidance or seek professional advice for your circumstances. Last reviewed 2026-07-06.